Auditory brainstem responses in 10 inbred strains of mice

The auditory brainstem response (ABR) is an evoked potential response of auditory activity in the auditory nerve and subsequent fiber tracts and nuclei within the auditory brainstem pathways. The threshold, amplitude, and latency analysis of the ABR provides information on the peripheral hearing status and the integrity of brainstem pathways. In this study, we compared the threshold, amplitude, and latency of ABRs recorded from 149 mice of 10 commonly used inbred strains (BALB/cJ, C3HeB/FeJ, C3H/HeJ, CAST/EiJ, CBA/CaJ, CBA/J, FVB/NJ, MRL/MpJ, NZB/BlNJ, and SJL/J) using clicks of different intensities. The ABR thresholds of these strains ranged from 32 to 43 dB SPL. The amplitude of both waves I and IV of ABRs, which increased monotonically with click intensity in most strains, differed significantly among different strains at each intensity tested. Moreover, the amplitude of both waves was inversely correlated with the body weight of each strain at most intensities tested. In general, the amplitude of wave IV was smaller than that of wave I resulting in the IV/I amplitude ratio of <1.0 in all strains. The peak latency of both waves I and IV decreased significantly with click intensity in each strain. However, this intensity-dependent decrease was greater for wave IV than for wave I such that the wave I-IV inter-peak latency also decreased significantly with increasing intensity. I-IV inter-peak latencies for MRL/MpJ, C3HeB/FeJ, NZB/BlNJ, and C3H/HeJ strains are longer than FVB/NJ, SJL/J, or CAST/EiJ. This work is the first step to study the genetic basis underlying strain-related differences in auditory pathway.